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Edward Szlyk - One of the best experts on this subject based on the ideXlab platform.
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determinatIon of antioxidant capacities of vegetable oils by Ferric Ion spectrophotometric methods
Talanta, 2008Co-Authors: Aleksandra Szydlowskaczerniak, Csilla Dianoczki, Katalin Recseg, Gyorgy Karlovits, Edward SzlykAbstract:Abstract Two Ferric-Ion-based total antioxidant capacity methods: 1,10-phenanthroline (Phen) and Ferric reducing antioxidant power (FRAP) were used for determinatIon of antioxidant capacities (AC) of the acetonic and methanolic extracts of vegetable oils. The obtained mean Phen and FRAP values for acetonic extracts of olive oils, rapeseed, rice and four sunflower oils (39.3–336.5 and 39.5–339.6 μmol Fe/100 g) were higher than for methanolic extracts (22.8–307.3 and 23.5–300.1 μmol Fe/100 g). However, antioxidant capacities of methanolic extracts of corn oil, blended oils and two sunflower oils with garden green flowers (56.5–312.9 and 53.9–306.5 μmol Fe/100 g for Phen and FRAP methods, respectively) were higher than for acetonic extracts of these oils (54.2–249.2 and 52.9–244.7 μmol Fe/100 g for Phen and FRAP methods, respectively). There is a linear and significant correlatIon between these two analytical methods ( r = 0.9989 and 0.9986 for acetonic and methanolic extracts). Also, total phenolic compounds (TPC) in the studied oils correlated with their antioxidant capacities determined by Phen and FRAP methods ( r = 0.9012, 0.7818 and 0.8947, 0.7830 for acetonic and methanolic extracts, respectively). The comparable precisIon (R.S.D. = 0.8–4.6%, 0.9–4.9% and 0.7–4.0%, 0.6–4.0% for acetonic and methanolic extracts, respectively) and sensitivity ( ɛ = 1.27 × 10 4 , 1.11 × 10 4 and 2.62 × 10 4 dm 3 mol −1 cm −1 ) for the proposed Phen and the modified FRAP methods, demonstrate the benefit of the Phen method in the routine analysis of antioxidant capacities of vegetable oils.
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determinatIon of antioxidant capacities of vegetable oils by Ferric Ion spectrophotometric methods
Talanta, 2008Co-Authors: Aleksandra Szydlowskaczerniak, Csilla Dianoczki, Katalin Recseg, Gyorgy Karlovits, Edward SzlykAbstract:Two Ferric-Ion-based total antioxidant capacity methods: 1,10-phenanthroline (Phen) and Ferric reducing antioxidant power (FRAP) were used for determinatIon of antioxidant capacities (AC) of the acetonic and methanolic extracts of vegetable oils. The obtained mean Phen and FRAP values for acetonic extracts of olive oils, rapeseed, rice and four sunflower oils (39.3-336.5 and 39.5-339.6 micromol Fe/100g) were higher than for methanolic extracts (22.8-307.3 and 23.5-300.1 micromol Fe/100g). However, antioxidant capacities of methanolic extracts of corn oil, blended oils and two sunflower oils with garden green flowers (56.5-312.9 and 53.9-306.5 micromol Fe/100g for Phen and FRAP methods, respectively) were higher than for acetonic extracts of these oils (54.2-249.2 and 52.9-244.7 micromol Fe/100g for Phen and FRAP methods, respectively). There is a linear and significant correlatIon between these two analytical methods (r=0.9989 and 0.9986 for acetonic and methanolic extracts). Also, total phenolic compounds (TPC) in the studied oils correlated with their antioxidant capacities determined by Phen and FRAP methods (r=0.9012, 0.7818 and 0.8947, 0.7830 for acetonic and methanolic extracts, respectively). The comparable precisIon (R.S.D.=0.8-4.6%, 0.9-4.9% and 0.7-4.0%, 0.6-4.0% for acetonic and methanolic extracts, respectively) and sensitivity (epsilon=1.27 x 10(4), 1.11 x 10(4) and 2.62 x 10(4)dm(3)mol(-1)cm(-1)) for the proposed Phen and the modified FRAP methods, demonstrate the benefit of the Phen method in the routine analysis of antioxidant capacities of vegetable oils.
Aleksandra Szydlowskaczerniak - One of the best experts on this subject based on the ideXlab platform.
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determinatIon of antioxidant capacities of vegetable oils by Ferric Ion spectrophotometric methods
Talanta, 2008Co-Authors: Aleksandra Szydlowskaczerniak, Csilla Dianoczki, Katalin Recseg, Gyorgy Karlovits, Edward SzlykAbstract:Abstract Two Ferric-Ion-based total antioxidant capacity methods: 1,10-phenanthroline (Phen) and Ferric reducing antioxidant power (FRAP) were used for determinatIon of antioxidant capacities (AC) of the acetonic and methanolic extracts of vegetable oils. The obtained mean Phen and FRAP values for acetonic extracts of olive oils, rapeseed, rice and four sunflower oils (39.3–336.5 and 39.5–339.6 μmol Fe/100 g) were higher than for methanolic extracts (22.8–307.3 and 23.5–300.1 μmol Fe/100 g). However, antioxidant capacities of methanolic extracts of corn oil, blended oils and two sunflower oils with garden green flowers (56.5–312.9 and 53.9–306.5 μmol Fe/100 g for Phen and FRAP methods, respectively) were higher than for acetonic extracts of these oils (54.2–249.2 and 52.9–244.7 μmol Fe/100 g for Phen and FRAP methods, respectively). There is a linear and significant correlatIon between these two analytical methods ( r = 0.9989 and 0.9986 for acetonic and methanolic extracts). Also, total phenolic compounds (TPC) in the studied oils correlated with their antioxidant capacities determined by Phen and FRAP methods ( r = 0.9012, 0.7818 and 0.8947, 0.7830 for acetonic and methanolic extracts, respectively). The comparable precisIon (R.S.D. = 0.8–4.6%, 0.9–4.9% and 0.7–4.0%, 0.6–4.0% for acetonic and methanolic extracts, respectively) and sensitivity ( ɛ = 1.27 × 10 4 , 1.11 × 10 4 and 2.62 × 10 4 dm 3 mol −1 cm −1 ) for the proposed Phen and the modified FRAP methods, demonstrate the benefit of the Phen method in the routine analysis of antioxidant capacities of vegetable oils.
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determinatIon of antioxidant capacities of vegetable oils by Ferric Ion spectrophotometric methods
Talanta, 2008Co-Authors: Aleksandra Szydlowskaczerniak, Csilla Dianoczki, Katalin Recseg, Gyorgy Karlovits, Edward SzlykAbstract:Two Ferric-Ion-based total antioxidant capacity methods: 1,10-phenanthroline (Phen) and Ferric reducing antioxidant power (FRAP) were used for determinatIon of antioxidant capacities (AC) of the acetonic and methanolic extracts of vegetable oils. The obtained mean Phen and FRAP values for acetonic extracts of olive oils, rapeseed, rice and four sunflower oils (39.3-336.5 and 39.5-339.6 micromol Fe/100g) were higher than for methanolic extracts (22.8-307.3 and 23.5-300.1 micromol Fe/100g). However, antioxidant capacities of methanolic extracts of corn oil, blended oils and two sunflower oils with garden green flowers (56.5-312.9 and 53.9-306.5 micromol Fe/100g for Phen and FRAP methods, respectively) were higher than for acetonic extracts of these oils (54.2-249.2 and 52.9-244.7 micromol Fe/100g for Phen and FRAP methods, respectively). There is a linear and significant correlatIon between these two analytical methods (r=0.9989 and 0.9986 for acetonic and methanolic extracts). Also, total phenolic compounds (TPC) in the studied oils correlated with their antioxidant capacities determined by Phen and FRAP methods (r=0.9012, 0.7818 and 0.8947, 0.7830 for acetonic and methanolic extracts, respectively). The comparable precisIon (R.S.D.=0.8-4.6%, 0.9-4.9% and 0.7-4.0%, 0.6-4.0% for acetonic and methanolic extracts, respectively) and sensitivity (epsilon=1.27 x 10(4), 1.11 x 10(4) and 2.62 x 10(4)dm(3)mol(-1)cm(-1)) for the proposed Phen and the modified FRAP methods, demonstrate the benefit of the Phen method in the routine analysis of antioxidant capacities of vegetable oils.
A. K. Mishra - One of the best experts on this subject based on the ideXlab platform.
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Role of Thiobacillus ferrooxidans and sulphur (sulphide)-dependent Ferric-Ion-reducing activity in the oxidatIon of sulphide minerals
Applied Microbiology and Biotechnology, 1996Co-Authors: A. Das, A. K. MishraAbstract:Thiobacillus ferrooxidans oxidized the sulphide minerals e.g., pyrite, pyrrhotite and copper concentrate under anaerobic conditIons in the presence of Ferric Ion as sole electron acceptor. Copper and iron were solubilized from sulphide ores by the sulphur (sulphide)-dependent Ferric-Ion oxidoreductase activity. Treatment of resting cells of T. ferrooxidans with 0.5% phenol for 30 min completely destroyed the iron- and copper-solubilizing activity. The above treatment destroyed the sulphur(sulphide)-dependent Ferric-Ion-reducing activity completely but did not affect the iron-oxidizing activity. The results suggest that sulphur(sulphide)-dependent Ferric-Ion-reducing activity actively participates in the oxidatIon of sulphide minerals under anaerobic conditIons. The activity of sulphur(sulphide)-dependent Ferric Ion reductIon in the solubilizatIon of iron and copper from the sulphide ores were also observed under aerobic conditIons in presence of sodium azide (0.1 μmol), which completely inhibits the iron-oxidizing activity.
Masaru Tanokura - One of the best experts on this subject based on the ideXlab platform.
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a novel mode of Ferric Ion coordinatIon by the periplasmic Ferric Ion binding subunit fbpa of an abc type iron transporter from thermus thermophilus hb8
Acta Crystallographica Section D-biological Crystallography, 2014Co-Authors: Shipeng Wang, Misaki Ogata, Shoichiro Horita, Jun Ohtsuka, Koji Nagata, Masaru TanokuraAbstract:Crystal structures of FbpA, the periplasmic Ferric Ion-binding protein of an iron-uptake ABC transporter, from Thermus thermophilus HB8 (TtFbpA) have been solved in apo and Ferric Ion-bound forms at 1.8 and 1.7 A resolutIon, respectively. The latter crystal structure shows that the bound Ferric Ion forms a novel six-coordinated complex with three tyrosine side chains, two bicarbonates and a water molecule in the metal-binding site. The results of gel-filtratIon chromatography and dynamic light scattering show that TtFbpA exists as a monomer in solutIon regardless of Ferric Ion binding and that TtFbpA adopts a more compact conformatIon in the Ferric Ion-bound state than in the apo state in solutIon.
Takehiro Kamiya - One of the best experts on this subject based on the ideXlab platform.
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functIonal characterisatIon of two Ferric Ion coordinatIon modes of ttfbpa the periplasmic subunit of an abc type iron transporter from thermus thermophilus hb8
Metallomics, 2019Co-Authors: Peng Lu, Yoshitaka Moriwaki, Mimin Zhang, Yukie Katayama, Yi Lu, Ken Okamoto, Tohru Terada, Kentaro Shimizu, Mengyao Wang, Takehiro KamiyaAbstract:The Ferric Ion binding protein A of Thermus thermophilus HB8 (TtFbpA) is the periplasmic subunit of an ABC-type iron transporter. Two Fe3+-bound crystal structures at pH 5.5 and pH 7.5 and one apo structure have been reported for TtFbpA. In additIon to three Tyr residues, TtFbpA coordinates with Fe3+ using two monodentate HCO3− and one H2O to form a six-coordinated mode at pH 5.5 or one bidentate CO32− to form a five-coordinated mode at pH 7.5. We investigated the biological significance of these Fe3+-bound forms of TtFbpA and the synergistic anIons (HCO3− and CO32−). Quantum mechanical calculatIons in silico indicated that only these coordinatIon modes were plausible out of six possibilities. Comparison of the crystal structures revealed a key motif, RZX1X2L(I/V), that would couple the Fe3+ coordinatIon mode and the TtFbpA protein conformatIon. Both gel filtratIon chromatography and isothermal titratIon calorimetry showed that TtFbpA could bind Fe3+ at pH 7.5 but not at pH 5.5. Isothermal titratIon calorimetry also revealed that the binding at pH 7.5 was a three-step endothermic reactIon that required NaHCO3. These results indicate that the holo structure at pH 5.5 is unstable in solutIon and may correspond to a transitIon state of TtFbpA–Fe3+ binding at pH 7.5 because HCO3− is much more abundant than CO32− at both pH values. ReorganisatIon of the synergistic Ions and coupled protein conformatIonal change will occur to form the stable TtFbpA–Fe3+ complex at pH 7.5, but not at pH 5.5. IdentificatIon of such a transitIon state will contribute to molecular design of novel FbpA inhibitors.